docs: ica tx encoding documentation added (#4169) (#4192)

* docs: added 'tx-encoding.md' file to docs

* feat: added tx encoding to frontend

* docs: improved tx encoding docs

* style(docs): moved tx encoding to bottom

* docs: improved tx encoding

* docs: improved ica tx encoding docs

* docs: in ica tx encoding, added small code blocks around some interface names

* docs: improved ica client docs + reordered tx encoding in sidebar

* docs(ica/cmd): updated docs of 'generate-packet-data'

* docs: improved ica tx encoding docs

(cherry picked from commit 585e56b)

Co-authored-by: srdtrk <59252793+srdtrk@users.noreply.github.com>

docs/.vuepress/config.js

@@ -256,6 +256,11 @@ module.exports = {
                   directory: false,
                   path: "/apps/interchain-accounts/parameters.html",
                 },
+                {
+                  title: "Tx Encoding",
+                  directory: false,
+                  path: "/apps/interchain-accounts/tx-encoding.html",
+                },
                 {
                   title: "Client",
                   directory: false,
@@ -286,7 +291,7 @@ module.exports = {
                       directory: false,
                       path: "/apps/interchain-accounts/legacy/keeper-api.html",
                     },
-                  ]
+                  ],
                 },
               ],
             },
@@ -397,7 +402,7 @@ module.exports = {
                   directory: false,
                   path: "/ibc/light-clients/setup.html",
                 },
-              ]
+              ],
             },
             {
               title: "Localhost",

docs/apps/interchain-accounts/active-channels.md

@@ -1,5 +1,5 @@
 <!--
-order: 8
+order: 9
 -->
 
 # Understanding Active Channels 

docs/apps/interchain-accounts/client.md

@@ -1,5 +1,5 @@
 <!--
-order: 7
+order: 8
 -->
 
 # Client
@@ -58,7 +58,7 @@ See below for example contents of `packet-data.json`. The CLI handler will unmar
 }
 ```
 
-Note the `data` field is a base64 encoded byte string as per the [proto3 JSON encoding specification](https://developers.google.com/protocol-buffers/docs/proto3#json).
+Note the `data` field is a base64 encoded byte string as per the tx encoding agreed upon during the channel handshake.
 
 A helper CLI is provided in the host submodule which can be used to generate the packet data JSON using the counterparty chain's binary. See the [`generate-packet-data` command](#generate-packet-data) for an example.
 
@@ -84,7 +84,7 @@ simd tx interchain-accounts host --help
 
 ##### `generate-packet-data`
 
-The `generate-packet-data` command allows users to generate interchain accounts packet data for input message(s). The packet data can then be used with the controller submodule's [`send-tx` command](#send-tx).
+The `generate-packet-data` command allows users to generate protobuf encoded interchain accounts packet data for input message(s). The packet data can then be used with the controller submodule's [`send-tx` command](#send-tx).
 
 ```shell
 simd tx interchain-accounts host generate-packet-data [message]

docs/apps/interchain-accounts/tx-encoding.md

@@ -0,0 +1,55 @@
+<!--
+order: 7
+-->
+
+# Transaction Encoding
+
+When orchestrating an interchain account transaction, which comprises multiple `sdk.Msg` objects represented as `Any` types, the transactions must be encoded as bytes within [`InterchainAccountPacketData`](https://github.com/cosmos/ibc-go/blob/v7.2.0/proto/ibc/applications/interchain_accounts/v1/packet.proto#L21-L26).
+
+```protobuf
+// InterchainAccountPacketData is comprised of a raw transaction, type of transaction and optional memo field.
+message InterchainAccountPacketData {
+  Type   type = 1;
+  bytes  data = 2;
+  string memo = 3;
+}
+```
+
+The `data` field must be encoded as a [`CosmosTx`](https://github.com/cosmos/ibc-go/blob/v7.2.0/proto/ibc/applications/interchain_accounts/v1/packet.proto#L28-L31).
+
+```protobuf
+// CosmosTx contains a list of sdk.Msg's. It should be used when sending transactions to an SDK host chain.
+message CosmosTx {
+  repeated google.protobuf.Any messages = 1;
+}
+```
+
+The encoding method for `CosmosTx` is determined during the channel handshake process. If the channel version [metadata's `encoding` field](https://github.com/cosmos/ibc-go/blob/v7.2.0/proto/ibc/applications/interchain_accounts/v1/metadata.proto#L22) is marked as `proto3`, then `CosmosTx` undergoes protobuf encoding. Conversely, if the field is set to `proto3json`, then [proto3 json](https://protobuf.dev/programming-guides/proto3/#json) encoding takes place, which generates a JSON representation of the protobuf message.
+
+## Protobuf Encoding
+
+Protobuf encoding serves as the standard encoding process for `CosmosTx`. This occurs if the channel handshake initiates with an empty channel version metadata or if the `encoding` field explicitly denotes `proto3`. In Golang, the protobuf encoding procedure utilizes the `proto.Marshal` function. Every protobuf autogenerated Golang type comes equipped with a `Marshal` method that can be employed to encode the message.
+
+## (Protobuf) JSON Encoding
+
+The proto3 JSON encoding presents an alternative encoding technique for `CosmosTx`. It is selected if the channel handshake begins with the channel version metadata `encoding` field labeled as `proto3json`. In Golang, the Proto3 canonical encoding in JSON is implemented by the `"github.com/cosmos/gogoproto/jsonpb"` package. Within Cosmos SDK, the `ProtoCodec` structure implements the `JSONCodec` interface, leveraging the `jsonpb` package. This method generates a JSON format as follows:
+
+```json
+{
+  "messages": [
+    {
+      "@type": "/cosmos.bank.v1beta1.MsgSend",
+      "from_address": "cosmos1...",
+      "to_address": "cosmos1...",
+      "amount": [
+        {
+          "denom": "uatom",
+          "amount": "1000000"
+        }
+      ]
+    }
+  ]
+}
+```
+
+Here, the `"messages"` array is populated with transactions. Each transaction is represented as a JSON object with the `@type` field denoting the transaction type and the remaining fields representing the transaction's attributes.

modules/apps/27-interchain-accounts/host/client/cli/tx.go

@@ -21,8 +21,8 @@ const (
 func generatePacketDataCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "generate-packet-data [message]",
-		Short: "Generates ICA packet data.",
-		Long: `generate-packet-data accepts a message string and serializes it
+		Short: "Generates protobuf encoded ICA packet data.",
+		Long: `generate-packet-data accepts a message string and serializes it using protobuf
 into packet data which is outputted to stdout. It can be used in conjunction with send-tx"
 which submits pre-built packet data containing messages to be executed on the host chain.
 `,